Display device

ABSTRACT

A display device includes a light emitting functional layer disposed between a first and second substrates; a first pixel which emits light to the second substrate and has a first pixel electrode disposed between the light emitting functional layer and the first substrate, a second electrode disposed between the light emitting functional layer and the second substrate, and a first reflecting layer disposed between the first pixel electrode and the first substrate; a second pixel which emits light to the first substrate side and has a second pixel electrode disposed between the light emitting functional layer and the first substrate, a second electrode disposed between the light emitting functional layer and the second substrate, and a second reflecting layer disposed between the second electrode and the second substrate; and a driving element which drives the first and second pixel electrodes is disposed above first substrate.

This is a Continuation Application of application Ser. No. 12/967,402filed Dec. 14, 2010 which is a National Phase of JP 2009-287303 filedDec. 18, 2009. The disclosure of the prior application is herebyincorporate by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a display device.

2. Related Art

Organic EL (electroluminescent) devices, which use anelectroluminescence phenomenon where light is emitted due to applying ofan electric current, are increasingly being used as display devices. Asa new use application in recent years, there has been considered a usemethod where both front and back surfaces can be seen at the same time.As a double-sided display organic EL device corresponding to this useapplication, in JP-A-2000-58260, for example, a configuration isproposed where light emitting functional layers including at least anelectroluminescence layer are formed on both sides of a cathode. Also,in JP-A-2001-332392, a configuration is proposed where a part of acathode is formed of a transmissive member, and in JP-A-2002-252089, aconfiguration is proposed where electrodes with a light emittingfunctional layer interposed therebetween, that is both an anode and acathode, are formed of transmissive members.

However, in the configuration where light emitting functional layers areformed on both sides of a cathode, there may be an increase inmanufacturing cost. Also, forming both an anode and a cathode of atransmissive member narrows the width of selection of electrodematerials so that there may be an impact on the light emittingcharacteristics and the like. In addition, in a more advanced useapplication, a use method is also proposed where a plurality of peoplefaces each other with a display device therebetween and meetings or thelike are carried out while looking at each other and at the displaydevice. For this use application, it is necessary that a transmissiveregion is provided in the display device. In addition, in order for theplurality of people who are facing each other to see an image which isnot reversed left and right, it is necessary that an image on one sideof the display device and an image on the other side are each formedindependently.

SUMMARY

An advantage of some aspects of the invention is that it solves at leastsome of the problems described above, and can be realized as embodimentsor application examples described below.

Application Example 1

According to this application example of the invention, there isprovided a display device including a first substrate; a secondsubstrate; a light emitting functional layer which is disposed betweenthe first substrate and the second substrate; a first pixel which emitslight to the second substrate side and is disposed above the firstsubstrate, the first pixel having a first pixel electrode disposedbetween the light emitting functional layer and the first substrate, asecond electrode disposed between the light emitting functional layerand the second substrate, and a first reflecting layer disposed betweenthe first pixel electrode and the first substrate; a second pixel whichemits light to the first substrate side and is disposed above the firstsubstrate, the second pixel having a second pixel electrode disposedbetween the light emitting functional layer and the first substrate, asecond electrode disposed between the light emitting functional layerand the second substrate, and a second reflecting layer disposed betweenthe second electrode and the second substrate; and a driving elementwhich drives the first pixel electrode and the second pixel electrode isdisposed above first substrate.

According to the configuration, by forming a two-layer reflecting layer,it is possible to emit light generated inside the light emittingfunctional layer from both the first substrate side and the secondsubstrate side. Accordingly, it is possible to realize a double-sideddisplay device where increases in manufacturing costs are suppressed.

Application Example 2

In regard to the display device mentioned above, a transmissive regionis disposed so that light can transmitted through the first substrateand the second substrate without the reflecting layer being disposed ina plan view.

According to the configuration, the opposite side through the displaydevice is visible while looking at a displayed image. Accordingly, in ameeting or the like, it is possible to realize a double-sided displaydevice where both the image and other people are visible.

Application Example 3

In regard to the display device mentioned above, the transmissive regionis a region where both the first pixel electrode and the second pixelelectrode are not disposed.

According to the configuration, light emitted by the light emittingfunctional layer can be suppressed in the transmissive region anddisplay quality can be improved.

Application Example 4

In regard to the display device mentioned above, the second electrodeand the light emitting functional layer of the first pixel are in thesame layer as the second electrode and the light emitting functionallayer of the second pixel.

According to the configuration, light can be emitted from both the firstsubstrate side and the second substrate side without an increase in theforming processes of the second electrode and the light emittingfunctional layer. Accordingly, it is possible to realize a double-sideddisplay device where increases in manufacturing costs are suppressed.

Application Example 5

In regard to the display device mentioned above, at least one of the twotypes of pixel electrodes of the first pixel electrode and the secondpixel electrode has three types of a sub pixel electrode of a red subpixel electrode, a green sub pixel electrode and a blue sub pixelelectrode which are each driven independently, and a pixel region whichcorresponds to the one pixel electrode is partitioned into three typesof sub pixel regions, a red sub pixel region which includes the red subpixel electrode in a plan view and emits red light, a green sub pixelregion which includes the green sub pixel electrode in a plan view andemits green light, and a blue sub pixel region which includes the bluesub pixel electrode in a plan view and emits blue light.

According to the configuration, it is possible to realize a double-sideddisplay device where at least one surface can display a color imagewhile increases in manufacturing costs are suppressed.

Application Example 6

In regard to the display device mentioned above, on a side opposite tothe reflecting layer side of the light emitting functional layer in thethree types of the sub pixel regions, a color filter is formedcorresponding to a color of light emitted from each of the sub pixelregions.

According to the configuration, it is possible to realize a double-sideddisplay device where at least one surface can display color images whileuse of the light emitting functional layer is shared between the subpixels.

Application Example 7

In regard to the display device mentioned above, the three types of thesub pixel electrodes include a semi-transmissive reflecting layer on aside opposite to the reflecting layer of the light emitting functionallayer, and an optical resonator structure, which optically resonateslight with a specific wavelength range, is formed between thesemi-transmissive reflecting layer and the reflecting layer.

According to the configuration, it is possible to realize a double-sideddisplay device where at least one surface can display color images whileuse of the light emitting functional layer is shared between the subpixel regions.

Application Example 8

In regard to the display device mentioned above, at least one of thefirst pixel electrode and the second pixel electrode is provided in azigzag shape.

According to the configuration, streaky unevenness can be suppressed inthe display region and display quality can be improved.

Application Example 9

In regard to the display device mentioned above, at least one of thefirst pixel electrode and the second pixel electrode is provided in acolumn shape.

According to the configuration, a reflecting layer formed on the secondsubstrate side can be provided in a strip shape and it is possible toeasily provide a mask formation film.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a perspective view showing an outline of an organic EL devicerelating to a first embodiment.

FIGS. 2A and 2B are diagrams illustrating an arrangement configurationof each region in a display region of the organic EL device.

FIGS. 3A to 3D are diagrams illustrating an arrangement of pixel regionsin the display region.

FIG. 4 is a circuit configuration diagram of the organic EL devicerelating to the first embodiment.

FIG. 5 is a schematic cross-sectional diagram of a pixel region of theorganic EL device relating to the first embodiment.

FIG. 6 is a circuit configuration diagram of an organic EL devicerelating to a second embodiment.

FIG. 7 is a schematic cross-sectional diagram of a pixel region of theorganic EL device relating to the second embodiment.

FIG. 8 is a circuit configuration diagram of an organic EL devicerelating to a third embodiment.

FIG. 9 is a schematic cross-sectional diagram of a pixel region of theorganic EL device relating to the third embodiment.

FIG. 10 is a circuit configuration diagram of an organic EL devicerelating to a fourth embodiment.

FIG. 11 is a schematic cross-sectional diagram of a pixel region of theorganic EL device relating to the fourth embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, as a display device relating to the invention, an organicEL device will be described with reference to the accompanying drawings.Here, the invention can be also realized by an EL device using inorganicEL materials as long as it is an EL device. However, the presentembodiment will be described using an example of an organic EL deviceusing organic EL materials as EL materials. Also, in regard to each ofthe diagrams below, each layer and part is set to a size so that it canbe recognized in the diagram, and the reduction scale of each layer andpart may differ from reality.

First Embodiment

FIG. 1 is a perspective view illustrating an outline of an organic ELdevice 91 relating to the first embodiment of the invention and organicEL devices relating to each of the other embodiments described later.The organic EL device 91 has a display region 100 where both the uppersurface and lower surface substantially overlap in a plan view. Asurface seen with an eye 80 on a left side is an upper surface 3 whichis a first surface, and a surface seen with an eye 80 on a right side isa lower surface 4 which is a second surface.

From the upper surface 3, a first display light 5 is irradiated, andfrom the lower surface 4, a second display light 6, which is differentdisplay light from the first display light 5, is irradiated. “Differentdisplay light” refers to light forming a different image. Accordingly,the organic EL device 91 can display images which are each different totwo viewers who are positioned to be facing with the organic EL device91 therebetween. Here, different images cannot be formed in the casewhere a light emitting functional layer 15 which is described later(refer to FIG. 5) is interposed between a pair of electrodes which areformed of transmissive materials and the same display light isirradiated from both the front and back surfaces (the upper and lowersurfaces). That is, an image where left and right direction is correctas shown in the diagram cannot be displayed to the two viewers, and animage which is reversed left and right is displayed to either one of theviewers. Accordingly, at the least, text information cannot be correctlydisplayed.

The organic EL device 91 of the embodiment can display a common image totwo viewers without being reversed left and right by displaying imageswhich are each different on both the front and back surfaces (the uppersurface 3 and the lower surface 4) by sharing the use of the lightemitting functional layer 15 described later. Also, in the displayregion 100, a transmissive region (a region where a portion of externallight 7 can pass through) is formed in a regular manner. Accordingly,two viewers who are facing each other with the organic EL devicetherebetween can see an image formed in the display region 100 as wellas the face of the other person. Therefore, in a meeting or the like, itis possible to carry out so-called face-to-face conversation whilelooking at an image (image information) without having to change a lineof sight.

FIGS. 2A and 2B are diagrams illustrating an arrangement configurationof each region in the display region 100 of the organic EL device 91 andorganic EL devices relating to each of the other embodiments describedlater. As the regions, there are three types of regions, a first pixelregion 41 which irradiates the first display light 5 toward the uppersurface, a second pixel region 42 which irradiates the second displaylight 6 toward the lower surface, and a transmissive region 43 where aportion of external light 7 can pass through. The three types of theregions are formed in the display region 100 in a regular manner.

FIG. 2A shows a configuration where each region (41, 42, 43) is disposedin individual columns (in the Y direction of FIG. 4 and the like). Thearrangement configuration has an advantage in that, compared to a zigzagarrangement, it is easier to form a second reflecting layer 14 (refer toFIG. 5) described later. Also, there is also an advantage in that afirst reflecting layer 13 (refer to FIG. 5) described later can beformed in a strip shape so as to span across a plurality of first pixelregions 41. Furthermore, the arrangement configuration is effective alsoin the case where the area of each region (41, 42, 43) is different.Here, in this diagram, each region is disposed in columns in a verticaldirection, but it is also possible to have an arrangement where eachregion is disposed in a row shape in a horizontal direction (an Xdirection in FIG. 4).

FIG. 2B shows a configuration where each region (41, 42, 43) is disposedin a zigzag shape. Due to the arrangement, a relatively smooth imagedisplay is possible. A column arrangement as shown in FIG. 2A is adoptedin the organic EL device 91 and organic EL devices relating to each ofthe other embodiments described later. However, the arrangement is notlimited to this, and it is possible for a zigzag arrangement as shown inFIG. 2B to be adopted in all of the embodiments.

FIGS. 3A to 3D are diagrams illustrating cases where each region (41,42, 43) is further partitioned. Mainly, in organic EL devices of thesecond, third and forth embodiments described later, a case is shownwhere the first pixel region 41 and the second pixel region 42 arepartitioned as sub pixel regions according to the color of irradiatedlight. FIG. 3A shows each region (41, 42, 43) of the organic EL device91 relating to the embodiment. The organic EL device 91 displays inblack and white so that neither the first pixel region 41 nor the secondpixel region 42 have sub pixel regions. That is, both of the pixelregions (41, 42) can irradiate white light at an arbitrary intensity butcannot irradiate colored light. Here, “white light” refers to not justpure white light but uses a concept that, although there is slightchromaticity, monochromatic light where chromaticity cannot change isalso included.

FIG. 4 is a circuit configuration diagram of the organic EL device 91relating to the first embodiment. The organic EL device 91 is providedwith the display region 100 and a peripheral region (with no symbols)formed in a peripheral portion of the display region. In the displayregion 100, a plurality of scanning lines 103 extending in an Xdirection, a plurality of signal lines 104 extending in a Y direction,and a plurality of power source lines 106 extending in the same Ydirection are formed. In each rectangular partition where the Xdirection is specified by the signal lines 104 and the power sourcelines 106 and the Y direction is specified by the scanning lines 103,first organic EL pixels (referred to as “first pixels” hereinafter) 31and second organic EL pixels (referred to as “second pixels”hereinafter) 32 are formed in columns as shown in FIG. 2A. Here, in thedescription below, a collective term for the first pixels 31 and thesecond pixels 32 is “organic EL pixels (31, 32).” This is the same forother components which will be described later.

The first pixels 31 are pixels corresponding to the first pixel region41 and are configured by an organic EL element 29 provided with a firstpixel electrode 35 (refer to FIG. 5) and other components which will bedescribed later. The second pixels 32 are pixels corresponding to thesecond pixel region 42 and are configured by an organic EL element 29provided with a second pixel electrode 36 (refer to FIG. 5) and othercomponents which will be described later. As the organic EL device 91relating to the embodiment is a device displaying black and whiteimages, there is no distinguishing of the color of light to beirradiated by each pixel. Here, the organic EL pixels (31, 32) is afunctional concept configured by each component of the organic ELelement 29 and the like. The pixel regions (41, 42) are regions whichirradiate display light and are a planar concept. Here, the transmissiveregion 43 is disposed in the display region 100, but as the transmissiveregion 43 is a region which is not formed by the organic EL element 29and the like, it is not shown in FIG. 4 which is a circuit diagram.

The organic EL device 91 is an active matrix display device and each ofthe organic EL pixels (31, 32) is formed of a switching TFT (thin filmtransistor) 108 which supplies a scanning signal to a gate electrode 23(refer to FIG. 5) via the scanning lines 103, a holding capacitor 110which holds an image signal supplied from the signal lines 104 via theswitching TFT 108, a driving TFT 112 which supplies an image signal heldby the holding capacitor 110 to the gate electrode 23, the organic ELelement 29 (refer to FIG. 5) in which driving electric current flowsfrom the power source lines 106 via the driving TFT 112, and the like.

In the peripheral region, a scanning line driving circuit 120 and asignal line driving circuit 130 are formed. The scanning line drivingcircuit 120 sequentially supplies scanning signals to the scanning lines103 in correspondence with each type of signal supplied by an externalcircuit which is not shown. The signal line driving circuit 130 suppliesimage signals to the signal lines 104. In the power source lines 106, animage driving current is supplied from an external circuit which is notshown. The operations of the scanning line driving circuit 120 and thesignal line driving circuit 130 are synchronized with each other by asynchronizing signal supplied from an external circuit via asynchronizing signal line 140.

When the scanning lines 103 are driven and the switching TFT 108 is inan on state, the potential of the signal lines 104 at that point in timeis held by the holding capacitor 110, and the level of the driving TFT112 is decided in correspondence with the state of the holding capacitor110. Next, a driving current flows from the power source lines 106 to animage electrode via the driving TFT 112, so that the organic EL element29 emits light corresponding to the size of the driving current toirradiate as display light (5, 6) from the pixel regions (41, 42)corresponding to each of the pixels (31, 32).

FIG. 5 is a schematic cross-sectional diagram of the display region 100of the organic EL device 91 (refer to FIGS. 1 and 2) relating to thefirst embodiment. As shown in the diagram, the organic EL device 91 isconfigured by an element substrate 10, an opposing substrate 11 andcomponents formed between this pair of substrates. The upper surface(the first surface) 3 is a surface on a side opposite to the opposingsubstrate 11 side, that is, a surface on a side opposite to a side whereeach component, which will be described later, on the opposing substrate11 is formed. The lower surface (the second surface) 4 is a surface on aside opposite to the element substrate 10 side, that is, a surface on aside opposite to a side where each component on the element substrate 10is formed.

The display region 100 is provided with a total of three types of theregions, in a plan view as described above, the first pixel region 41which irradiates first display light 5 from the upper surface 3, thesecond pixel region 42 which irradiates second display light 6 from thelower surface 4, and the transmissive region 43 which at least a portionof external light 7 can pass through. In addition, in the first pixelregion 41, the first pixels 31 are formed, and in the second pixelregion 42, the second pixels 32 are formed. As shown in the diagram, thedifference between the first pixels 31 and the second pixels 32 is theformation position of the reflecting layers (13, 14) in the verticaldirection of the substrate surface. Due to a difference in the formationposition, the irradiating direction of the display light (5, 6) can bechanged. Here, when symbols are written in brackets and separated by acomma as described above, this refers to both a “first component” and a“second component.”

The transmissive region 43 is configured of each layer formed oversubstantially the entire surface of the display region 100 and the pairof substrates in the vertical direction, and the reflecting layers (13,14) and the like described above are not formed. In addition, each layerformed over the entire surface is formed of transmissive orsemi-transmissive materials. Also, the element substrate 10 and theopposing substrate 11 are formed of transmissive materials such as glassor the like. Accordingly, at least a portion of external light 7 canpass through the transmissive region 43 through the organic EL device91.

Here, the pixel electrodes (35, 36) are not formed in the transmissiveregion 43, because it is not necessary to pass an electric currentthrough the light emitting functional layer 15 described later. However,if the pixel electrodes are formed of ITO or the like which havetransmissive properties (which will be described later), the pixelelectrodes (35, 36) may be formed in a configuration where a layer ofthe same material is electrically isolated from the pixel electrodes.

Each component configuring the organic EL pixels (31, 32) will bedescribed below in order from the element substrate 10 side. Here, theorganic EL device 91 relating to the embodiment and organic EL devicesrelating to each of the other embodiments described later have thecharacteristic that the irradiating directions of the display light fromthe first pixels 31 and the second pixels 32 are different.Consequently, in FIG. 5, among the components configuring both thepixels (31, 32) described above, the organic element 29 and the drivingTFT (hereinbelow, simply referred to as “TFT”) 112 which drives theorganic EL element is shown and the switching TFT 108 and the holdingcapacitor 110 are not shown in the diagram.

The TFT 112 is formed on the upper layer of the element substrate 10. Inthe boundary surface between the element substrate 10 and the TFT 112, aprotective layer may be separately formed. Here, “upper” and “upperlayer” refer to the opposing substrate 11 side. The TFT 112 is formed ofa semiconductor layer 21, the gate electrode 23 formed by patterning thesame layer as the scanning lines 103, a gate insulating layer 70 formedbetween the semiconductor layer 21 and the gate electrode 23, and thelike. The region of the semiconductor layer 21 which is overlapped withthe gate electrode 23 in a plan view is the channel region 22, and asource region 25 and a drain region 26 are formed on both sides of thechannel region 22. Here, the gate electrode 23 has a configuration whereTi (titanium), AlCu (an aluminum copper alloy) and TiN (titaniumnitride) are laminated in this order from the element substrate 10 side.

In the upper layer of the TFT 112, an interlayer insulating layer 71 isformed by laminating an inorganic insulating material such as siliconnitride, silicon oxide or the like and a organic material such asacrylic resin or the like. In the drain region 26, the pixel electrodes(35, 36) are electrically connected via a contact hole 27 formed bylocally etching the interlayer insulating layer 71. It is necessary thatthe formation material of the pixel electrodes (35, 36) be transmissiveand conductive, and also that the formation material have a higher workfunction than a cathode 19 which is a common electrode described later.Therefore, in the organic EL device 91, the pixel electrodes (35, 36)are formed of ITO (an alloy of indium oxide and tin oxide) which is atransmissive and conductive material. IZO (an alloy of indium oxide andzinc oxide) may be used instead of ITO. Furthermore, PEDOT, which is atransmissive and conductive material and does not contain metal, may beused.

In the lower layer of the first pixel electrode 35, the first reflectinglayers 13 and a protective layer 28 which covers the first reflectinglayer is formed. It is preferable that the formation material of thefirst reflecting layer 13 (and the second reflecting layer 14 describedlater) is a material which has high reflectivity and is superior inworkability (patterning). Accordingly, the first reflecting layer 13(and the second reflecting layer 14 described later) of the organic ELdevice 91 is formed of Al (aluminum) or the like. The first reflectinglayer 13 has a thickness of approximately 80 nm and is formed bypatterning the Al layer formed over the entire surface.

The protective layer 28 is formed of silicon oxide and performs afunction of protecting the first reflecting layer 13 during formation ofthe first pixel electrode 35. Also, as silicon nitride is an insulatingmaterial, there can be electrical insulation between the first pixelelectrode 35 and the first reflecting layer 13. Accordingly, if there isa configuration where the entire surface of the first reflecting layer13 is covered by the protective layer 28 formed of silicon nitride, thefirst reflecting layer 13 can be formed in a strip shape so as to spanacross a plurality of the first pixel regions 41 adjacent in the Ydirection (refer to FIG. 4) and not formed in an island shape. That is,in the Y direction, there can be a configuration where the first pixelelectrode 35, which is patterned in an island shape, is disposed in theformation region of the first reflecting layer 13 in a plan view.

In addition, also in the X direction, there can be a configuration wherethe first pixel electrode 35 is disposed in the formation region of thefirst reflecting layer 13. That is, the first reflecting layer 13 iswider in a plan view than the first pixel electrode 35 in regions otherthan the formation region of the contact hole 27. That is, the firstreflecting layer 13 can be formed to cover the first pixel electrode 35in a plan view.

Here, it is not essential that the first pixel electrode 35 istransmissive so that it can be formed of a reflective material such asAg (silver) or the like. In that case, the first pixel electrode 35 canalso be used as the first reflecting layer 13. In addition, theprotective layer 28 is not necessary. Furthermore, the first reflectinglayer 13 (and the second reflecting layer 14 described later) may beformed, not by patterning using a photolithography method or the like,but by combining film formation and patterning using a mask filmformation method such as a mask deposition method or the like.

In the upper layer of the element substrate 10 where the pixelelectrodes (35, 36) are formed, the light emitting functional layer 15is formed over the entire surface. Accordingly, in the two types ofregions of the first pixel region 41 and the second pixel region 42, thelight emitting functional layer 15 is a layer which is shared.Accordingly, in the production of the organic EL device 91 relating tothe embodiment (and organic EL devices relating to each of the otherembodiments described later), the formation process of the lightemitting functional layer 15 is only performed once.

The light emitting functional layer 15 is a collective term, andspecifically, the light emitting functional layer 15 is formed bylaminating a total of four layers, a hole injection layer, a holetransport layer, an organic EL layer and an electron transport layer, inthat order from the element substrate 10 side. It may be considered thatthere are a total of five layers including an electron injection layerformed in the upper layer of the electron transport layer. As theorganic EL device 91 of the invention is, not a color but, a black andwhite (monochrome) display device, the organic EL layer is a layer thatemits white light. Accordingly, the light emitting functional layer 15is a layer with a white light emitting function. Here, the organicdisplay device described above is not limited to a layer formed of asingle material. In the organic EL layer, layers which each emit lightof different colors may be laminated so that, in total, white light isirradiated. Also, it is not necessary that pure white light isirradiated and light slightly tinged with color may be irradiated.

In the upper layer of the light emitting functional layer 15, thecathode 19 as a common electrode is formed over the whole surface in thesame manner as the light emitting functional layer 15. The organic ELelement 29 is the laminated body of the cathode 19, the light emittingfunctional layer 15, and the pixel electrodes (35, 36). When an electricvoltage is applied to the pixel electrodes (35, 36) via the TFT 112,electric current flows between the pixel electrodes (35, 36) and thecathode 19 via the light emitting functional layer 15, and light isemitted corresponding to the amount of electric current by the organicEL layer included in the light emitting functional layer 15.

As described above, the first reflecting layer 13 is formed on theelement substrate 10 side of the first pixel electrode 35. Accordingly,in regard to the first pixel electrode 41, the first reflecting layer 13is positioned between the light emitting functional layer 15 and theelement substrate 10, and emitted light directed toward the elementsubstrate 10 side is reflected toward to the opposing substrate 11 side.Also, in regard to the first pixel electrode 41, emitted light directedtoward the opposing substrate 11 side is irradiated in that state asfirst display light 5 from the first surface 3, that is, from theopposing substrate 11 side. Accordingly, all of the emitted lightgenerated by the first pixels 31 is irradiated as first display light 5from the first surface 3, that is, from the opposing substrate 11 side.

As the organic EL device 91 is a black and white display organic ELdevice, a resonator structure is not needed for the organic EL element29. Accordingly, the cathode 19 is not necessarily required to havesemi-transmissivity and may be transmissive (translucent). On the otherhand, only a portion of external light 7 is required to pass through thetransmissive region 43 (refer to FIGS. 2A and 2B) so that it is notnecessary that the cathode 19 is completely transmissive. Accordingly,the cathode 19 may have transmissivity or may have semi-transmissivity.

Also, it is necessary that the cathode 19 is conductive as it is anelectrode, and furthermore, it is necessary that it is formed from amaterial which has a lower work function than the formation material ofpixel electrodes (35, 36) so that electron injection properties can besecured. In regard to the organic EL device 91, on top of 2 nm of Al and1 nm of LiF (lithium fluoride) laminated as the electron injectionlayer, ITO is laminated as the cathode 19 to secure transmissivity andelectron injection properties.

In the upper layer of the cathode 19 in the second pixel region 42, thesecond reflecting layer 14 is formed. The second reflecting layer 14 isformed of Al and has a thickness of 80 nm in the same manner as thefirst reflecting layer 13. However, it is preferable that the formationmethod of the second reflecting layer 14 is due to a mask film formationmethod such as a mask deposition method or the like in order to alsosuppress damage to the cathode 19 which is a base. Different from thefirst reflecting layer 13, it is not necessary that the secondreflecting layers 14 are electrically independent from each other. Also,it is not a problem even if the second reflecting layer 14 overlaps withthe contact hole 27 in a plan view. Accordingly, in the embodiment, thesecond reflecting layer 14 can be formed in a strip shape extending inthe Y direction (refer to FIG. 4).

The second reflecting layer 14 has a function as a cathode wiring(supplementary wiring), as well as a function of reflecting lightgenerated in the light emitting functional layer 15 to the elementsubstrate 10 side. As described above, the cathode 19 is formed to beextremely thin so as to exhibit transmissivity. Accordingly, the cathode19 has high surface resistance and a tendency for a reduction in theamount of electric current flowing in the organic EL layer due to avoltage drop in the vicinity of the center of the organic EL device. Asthe second reflecting layer 14 is laminated on the upper surface of thecathode 19 with nothing therebetween, the second reflecting layer 14 andthe cathode 19 are electrically integrated.

In addition, the second reflecting layer 14 is formed to have athickness of 80 nm to be sufficiently thick compared to the layerthickness of the cathode 19, and is formed regularly in the displayregion 100. Accordingly, in the region where transmissivity is notrequired, the second reflecting layer 14 increases the layer thicknessof the cathode 19 in practice and reduces the surface resistance of thecathode 19. Due to the reduction in surface resistance, a voltage dropis suppressed even in the vicinity of the center. Thus, the organic ELdevice 91 can display an improved quality image with hardly anydifference in luminance and the like in the center section and theperipheral section.

The second pixels 32 do not have a reflecting layer on the lower layerof the second pixel electrode 36. Thus, among emitted light generated inthe light emitting functional layer 15, emitted light directed towardthe element substrate 10 side is irradiated in that state as seconddisplay light 6 from the second surface 4. On the other hand, in theupper layer of the light emitting functional layer 15, as the secondreflecting layer 14 is provided, the emitted light directed toward theopposing substrate 11 side is reflected by the second reflecting layer14 to be irradiated from the second surface 4 side as second displaylight 6 toward the element substrate 10 side. Accordingly, substantiallyall of the emitted light generated by the second pixel region 42 isirradiated from the second surface 4 side as second display light 6.

A sealing layer 79 is formed on the upper layer of the cathode 19 onwhich the second reflecting layer 14 is formed, that is, between thecathode 19 and the opposing substrate 11. The sealing layer 79 is shownin the diagram as a single layer, but in practice, is formed of alaminated body formed of a total of three layers, a cathode protectinglayer, an organic buffer layer, and a gas barrier layer which are formedin that order from the upper layer of the cathode 19, and an adhesivelayer having transmissivity which fills in between the laminated bodyand the opposing substrate 11. As all of the individual layersconfiguring the sealing layer 79 described above are formed fromtransmissive materials, at least a portion of external light 7 can passthrough the transmissive region 43. Accordingly, two people facing eachother through the organic EL device 91 can visually recognize eachother.

As is described above, in the organic EL device 91 of the embodiment, atleast a portion of external light 7 can pass through the transmissiveregion 43, first display light 5 is irradiated to the opposing substrate11 side in the first pixel region 41, and second display light 6 isirradiated to the element substrate 10 side in the second pixel region42. Therefore, a light blocking layer such as the reflecting layers (13,14) is not formed in the transmissive region, and on the other hand, inthe pixel regions (41, 42), light generated by the light emittingfunctional layer 15 is irradiated only to one side due to the reflectinglayers (13, 14).

Here, in the region where the pixel electrodes (35, 36) are formed, asemitted light is generated by the light emitting functional layer 15, itis necessary to include the pixel electrodes (35, 36) in the reflectinglayers (13, 14) in a plan view so as to suppress the irradiating ofdisplay light (5, 6) toward the opposite side. However, in the firstpixel region 41, the first reflecting layer 13 cannot be formed in theformation region of the contact hole 27. Also, as the reflecting layers(13, 14) reflect external light, there is a possibility of a reductionin display quality if the portion where the reflecting layers (13, 14)and the pixel electrodes (35, 36) do not overlap, that is, the portionwhere the reflecting layers (13, 14) protrude out from the pixelelectrodes (35, 36) in a plan view, is formed to be excessively wide.

In order to suppress this phenomenon, in the region other than thetransmissive region 43, a partition (not shown) may be formed in aregion surrounding the pixel electrodes (35, 36) in a plan view. In theregion described above, by forming a partition, which is formed of aninsulating material with light blocking properties, between the pixelelectrodes (35, 36) and the light emitting functional layer 15, both theirradiating of emitted light from the light emitting functional layer 15toward a nonpreferred side and the reflecting of external light 7 can besuppressed. Thus, image quality can be improved.

Effects of the Embodiment

As described above, the organic EL device 91 has two types of pixels,the first pixels 31 and the second pixels 32. Both the pixels (31, 32)have a similar configuration and the only difference is the formationposition of the reflecting layers (13, 14) (position in the verticaldirection).

Here, even in terms of general organic EL devices, it is typical that areflecting layer is formed in order to irradiate display light only fromeither one of the element substrate 10 side or the opposing substrate 11side. Accordingly, the organic EL device 91 relating to the embodiment,by only newly forming a single layer of reflecting layer, display lightcan be irradiated from both surfaces of the first surface 3 and thesecond surface 4. Also, as the organic EL device 91 is an active matrixdisplay device, different emitted light can be generated betweenadjacent pixels (31, 32). Accordingly, by slightly increasing the numberof manufacturing processes, that is, by only increasing themanufacturing costs, the organic EL device 91 can irradiate displaylight from both surfaces of the first surface 3 and the second surface 4to form images which are each different in the display regions 100 ofboth of the surfaces (3, 4).

Here, different images described above include images where the sametext information has been reversed left and right. Images can be formedon the display regions 100 of both surfaces also in the case where thepixel electrodes (35, 36) and the cathode 19 are formed of transmissivematerials without using a structure like the organic EL device 91.However, when the image on one of the surfaces is used as a reference,left and right are reversed in the other surface so that at least textinformation cannot be correctly displayed.

The organic EL device 91 can form text information without left andright reversing on the display regions 100 of both surfaces. Thus, in ameeting or the like, a plurality of people can carry out a conversationwhile visually recognizing shared information through the organic ELdevice. Furthermore, as there is a transmissive region 43 in the displayregion 100, facial expressions and the like of a person on the otherside of the display device and images can be simultaneously visuallyrecognized. Accordingly, by using the organic EL device 91 relating tothe embodiment, a meeting or the like, which is carried out whilereferencing image information such as text information, can beeffectively accomplished. Furthermore, as both of the surfaces (3, 4)can perform display, the organic EL device 91 and organic EL devices(92, 93, 94) relating to each of other embodiments described later candisplay advertising with no blind spots in the cases where they are usedfor digital signage.

Here, in FIGS. 2A and 2B and FIG. 3A, the area ratio of the three typesof the regions (41, 42, 43) which are formed in the display region 100are shown in the diagram to be substantially 1:1:1. However, the arearatio is not limited to the above value and can be arbitrarily set.Also, when it is not necessary to see a face and facial expressions ofanother person and the like, there can be only two types of regions, thefirst pixel region 41 and the second pixel region 42, without thetransmissive region 43 being formed.

Second Embodiment

Next, the second embodiment of this invention will be described. Theorganic EL device 92 relating to the present embodiment has the samepurpose of use and configuration as the organic EL device 91 relating tothe first embodiment, and the components are also the same. That is, asshown in FIG. 1, both the first surface 3 and the second surface 4 havedisplay regions 100 which substantially overlap in a plan view, and bothof the surfaces (3, 4) can display images which are each different. Inaddition, due to the transmissive region 43 (refer to FIGS. 2A and 2Band the like) formed in the display region 100, the opposing side (thatis, the opposite side) through the organic EL device can be visuallyrecognized. The arrangement configuration of the three types of regionsincluding the transmissive region 43 is also the same. That is, a columnarrangement as shown in FIG. 2A has been adopted.

The organic EL device 92 is different from the organic EL device 91 ofthe first embodiment in that it is a color display and not a black andwhite display. Accordingly, the two regions other than the transmissiveregion 43 are further partitioned into sub pixel regions which irradiateany one of the three primary colors.

In FIG. 3B, an arrangement configuration of sub pixel regions in thepixel regions (41, 42) of the organic EL device 92 is shown. As shown inthe diagram, the first pixel region 41 is partitioned into sub pixelregions, which irradiate any one of three primary colors, a first redsub pixel region 51 r which irradiates red light, a first green subpixel region 51 g which irradiates green light, and a first blue subpixel region 51 b which irradiates blue light.

In the same manner, the second pixel region 42 is also partitioned intosub pixel regions, which irradiate any one of three primary colors, asecond red sub pixel region 52 r which irradiates red light, a secondgreen sub pixel region 52 g which irradiates green light, and a secondblue sub pixel region 52 b which irradiates blue light. Accordingly,both pixel regions (41, 42) can irradiate light of an arbitrary colorobtained by mixing the three primary colors by an arbitrary ratio.Accordingly, the organic EL device 92 can display (form) a color imagein the display regions 100 on the sides of both the first surface 3 andthe second surface 4.

Here, in the description below, in the case when, for example, the firstsub regions 51 (r, g, b) are described, it refers to the three types ofthe sub pixel regions described above in the first pixel region 41included as shown in FIG. 3B.

FIG. 6 is a circuit configuration diagram of the organic EL device 92.FIG. 6 is equivalent to FIG. 4 of the first embodiment described above,and FIG. 7 described later is equivalent to FIG. 5 of the firstembodiment. As described above, the organic EL device 92 has the samepurpose of use and the like as the organic EL device 91 relating to thefirst embodiment. The configuration also is the same except for that itis a color display and not a black and white display. Therefore, in FIG.6 and FIG. 7, common configuration components are given the same symbolsand a part of the description is not repeated.

The organic EL device 92 is partitioned into the display region 100 anda peripheral region surrounding the display region 100 in a plan view.In the peripheral region, the scanning line driving circuit 120, thesignal line driving circuit 130, and the synchronizing signal line 140which synchronizes both the driving circuits are formed. In the displayregion 100, the plurality of scanning lines 103 extending in the Xdirection, the plurality of signal lines 104 extending in the Ydirection, and the plurality of power source lines 106 extending in thesame Y direction are formed. In addition, in the display region 100, thefirst pixels 31 and the second pixels 32 are formed in columns as shownin FIG. 2A described above. Here, as described above, the first pixels31 and the second pixels 32 can also be formed in a zigzag shape and notin columns. Also, in the same manner as the organic EL device 91described above, as FIG. 6 is a circuit diagram, the transmissive region43 (refer to FIGS. 2A and 2B) is not shown.

The pixels (31, 32) of the organic EL device 92 is configured of threetypes of sub pixels so as to correspond to the relation between the subpixel regions and the pixel regions described above. That is, the firstpixels 31 are configured by three types of sub pixels, first red subpixels 33 r, first green sub pixels 33 g, and first blue sub pixels 33b. In the same manner, the second pixels 32 are configured by threetypes of sub pixels, second red sub pixels 34 r, second green sub pixels34 g, and second blue sub pixels 34 b. Each lower case letter includedin each of the symbols refers to the color of the emitted light which isirradiated from each of the sub pixel regions (51, 52) described abovecorresponding to each of the sub pixels (33, 34). It is the same forother configuration components (color filters and the like describedlater).

Each of the sub pixels (33, 34) can convert white light generated by thelight emitting functional layer 15 to any one of three primary colors ofred light, green light, or blue light due to color filters 75 (r, g, b)described later and the resonator structure, and can irradiate thecolored light from each of the sub pixel regions (51, 52). Here, “eachsub pixel (33, 34)” refers to a common term for the six types of the subpixels described above, and “each sub pixel region (51, 52)” refers to acommon term for the six types of the sub pixel regions described above.

As shown in the diagram, the six types of the sub pixels (33, 34)described above are formed in each rectangular partition where the Xdirection is specified by the signal lines 104 and the power sourcelines 106 and the Y direction is specified by the scanning lines 103. Inaddition, each sub pixel (33, 34) is provided with the organic ELelement 29, the switching TFT 108, the holding capacitor 110, and thedriving TFT 112. In addition, a driving current flows from the powersource lines 106 to the organic EL element 29 via the driving TFT 112,so that the organic EL element 29 emits light corresponding to the sizeof the driving current in the same manner as the pixels (31, 32) in theorganic EL device 91 relating to the first embodiment. Accordingly, anamount of emitted light in each of the individual organic EL elements 29can be arbitrarily controlled. As a result, a color image can be formedin the display region 100.

FIG. 7 is a schematic cross-sectional diagram of the display region 100of the organic EL device 92. As shown in the diagram, the display region100 of the organic EL device 92 includes a total of three types of theregions, the first pixel region 41 which irradiates first display light5 from the first surface 3, the second pixel region 42 which irradiatessecond display light 6 from the second surface 4, and the transmissiveregion 43. In addition, as described above, the first pixel region 41and the second pixel region 42 further include three types of the subpixel regions. In addition, each of the sub pixel regions (51, 52)corresponds one-to-one with the sub pixels (33, 34) in a plan view.

That is, the first red sub pixel region 51 r corresponds to the firstred sub pixel 33 r, the first green sub pixel region 51 g corresponds tothe first green sub pixel 33 g, and the first blue sub pixel region 51 bcorresponds to the first blue sub pixel 33 b. In the same manner, thesecond red sub pixel region 52 r corresponds to the second red sub pixel34 r, the second green sub pixel region 52 g corresponds to the secondgreen sub pixel 34 g, and the second blue sub pixel region 52 bcorresponds to the second blue sub pixel 34 b.

As described above, the sub pixels (33, 34) have the same components asthe “pixels” of the organic EL device 91. That is, the sub pixels (33,34) are configured by the (driving) TFT 112, the organic EL element 29,and the switching TFT 108 and the holding capacitor 110 which are notshown in the diagrams, and the like. Accordingly, in the same manner tothe organic EL device 91 relating to the first embodiment, an arbitraryamount of light can be irradiated by controlling voltage applied betweena pair of electrodes configuring the organic EL element 29. Here, theorganic EL element 29 is essentially a laminated body of a pair ofelectrodes (the cathode 19 and the pixel electrodes (35, 36)) and thelight emitting functional layer 15. However, in FIG. 7, for descriptivepurposes, the organic EL element 29 is shown including the reflectinglayers (13, 14) or a semi-transmissive reflecting layer 12. Also, inFIG. 7, the protective layer 28 (refer to FIG. 5), which covers thefirst reflecting layer 13, is not shown in the diagram.

Each of the pixel electrodes (35, 36) of the organic EL device 92 isalso configured by three types of sub pixel electrodes. That is, thefirst pixel electrode 35 is configured by a first red sub pixelelectrode 37 r, a first green sub pixel electrode 37 g, and a first bluesub pixel electrode 37 b. The second pixel electrode 36 is configured bya second red sub pixel electrode 38 r, a second green sub pixelelectrode 38 g, and a second blue sub pixel electrode 38 b.

The light emitting functional layer 15 of the organic EL device 92 is alayer with a white light emitting function provided with an organic ELlayer which emits white light, in the same manner as the light emittingfunctional layer 15 of the organic EL device 91 of the first embodiment.In addition, by emphasizing light with a specific wavelength range inwhite light and irradiating the light after making it colored light, theorganic EL device 92 is able to perform color display. As a result, theorganic EL device 92 differs compared to the organic EL device 91 interms of the points below.

First, color filters 75 (r, g, b) are formed to correspond to each subpixel (33, 34). Next, the cathode 19 is formed of a material layer whichhas semi-transmissivity, that is, which has approximately 50%transmissivity. In addition, next, between the second sub pixelelectrodes 38 (r, g, b) and the element substrate 10, thesemi-transmissive reflecting layer 12, which is a material layer havingsemi-transmissivity, is formed in regard to the second sub pixels 34 (r,g, b). The semi-transmissive layer (the cathode 19 and thesemi-transmissive reflecting layer 12) is configured in a resonatorstructure by being combined with the reflecting layers (13, 14). In theorganic EL device 92, the emitted colored light is obtained by theresonator structure of and the function of the color filters 75 (r, g,b) described above.

First, light irradiated from the second surface 4 is described. Thesecond sub pixels 34 (r, g, b) are provided with the semi-transmissivereflecting layer 12 between the second sub pixel electrodes 38 (r, g, b)and the interlayer insulating layer 71 as described above, and thesecond reflecting layer 14 on the upper surface of the cathode 19. Inaddition, color filters 75 (r, g, b) are provided between the second subpixel electrodes 38 (r, b) and the element substrate 10. Here, thesemi-transmissive reflecting layer 12 is formed of Al or an MgAg alloywith a layer thickness of approximately 10 nm.

Approximately half of the light emitted by the light emitting functionallayer 15 is directed toward the opposing substrate 11 side and isreflected by the second reflecting layer 14 to be directed toward theelement substrate 10 side. Also, the remaining approximately half of thelight is directed directly toward the element substrate 10 side. Inaddition, the approximately half of the light directed toward theelement substrate 10 side passes through the semi-transmissivereflecting layer 12 and the color filter 75 described later and isirradiated from the second surface 4. The remaining approximately halfof the light is reflected by the semi-transmissive reflecting layer 12to be directed toward the opposing substrate 11 side. Then, the light isreflected by the second reflecting layer 14 to be directed again to thesemi-transmissive reflecting layer 12 side. The resonance is therepeating of the light, which is emitted by the light emittingfunctional layer 15, being reflected between the semi-transmissivereflecting layer 12 and the second reflecting layer 14. As a result,light with a specific wavelength range, which is determined by thedistance between the semi-transmissive reflecting layer 12 and thesecond reflecting layer 14, is emphasized.

The distance between the semi-transmissive reflecting layer 12 and thesecond reflecting layer 14 is resonant length. In the organic EL device92, the resonant length is formed to match the wavelength of irradiatedlight of each of the second sub pixel 34 (r, g, b) by changing thethickness of the second pixel electrode 36, that is, the thickness ofthe ITO layer, for each of the second sub pixel electrodes 38 (r, g, b).Accordingly, in regard to light which passes through thesemi-transmissive reflecting layer 12, red light is emphasized in thesecond red sub pixel 34 r, green light is emphasized in the second greensub pixel 34 g, and blue light is emphasized in the second blue subpixel 34 b.

The color filter 75 is a colored transmissive resin layer, and has afunction of improving color purity by allowing a higher ratio of lightwith a specific wavelength range to pass through compared to light witha different wavelength range to emphasize the light with the specificwavelength. Specifically, the red color filter 75 r has the function ofallowing a higher ratio of light with a wavelength range equivalent tored light to pass through, the green color filter 75 g has the functionof allowing a higher ratio of light with a wavelength range equivalentto green light to pass through, and the blue color filter 75 b has thefunction of allowing a higher ratio of light with a wavelength rangeequivalent to blue light to pass through. Light, which is light with aspecific wavelength range which has been emphasized by the resonatorstructure described above, becomes light with its color purity furtherimproved due to the color filter and is irradiated from the secondsurface 4.

Due to the resonator structure and the color filter described above, thesecond sub pixels 34 (r, g, b) can irradiate light with a specificwavelength range of any one of the three primary colors. Accordingly,the second pixels 32 provided with the sub pixels can irradiate light ofan arbitrary color (chromaticity), which has been obtained by mixing anarbitrary ratio of three primary colors of light, as second displaylight 6 from the second surface 4. Accordingly, the organic EL device 92can form color images on the second surface 4 side.

Next, light irradiated from the first surface 3 is described. The firstsub pixels 33 (r, g, b) are provided with the first reflecting layer 13between the first sub pixel electrodes 37 (r, g, b) and the interlayerinsulating layer 71 (via the protective layer which is not shown). Inaddition, as described above, the cathode 19 is formed of a materiallayer having semi-transmissivity. Accordingly, the resonator structureis formed between the first reflecting layer 13 and the cathode 19. Theresonant length of the resonator structure is set to a thicknessmatching the wavelength of the irradiating light of each of the firstsub pixels 33 (r, g, b) in the same manner as the resonant length withregard to the second pixels 32. Here, similar to the semi-transmissivereflecting layer 12, the formation material of the cathode 19 is Al oran MgAg alloy with a layer thickness of approximately 10 nm.

A color filter layer 76 is formed on the sealing layer 79 side of theopposing substrate 11 in regard to the first pixel region 41. Here, thecolor filter layer 76 is formed of the color filter 75 (r, g, b)corresponding to each emitted light color, a black matrix 75 k whichblocks light between adjacent color filters, and an overcoat layer 77which protects the color filter. Light, which is light with a specificwavelength range which has been emphasized by the resonator structuredescribed above, becomes light (colored light) with its color purityfurther improved due to the color filter. Accordingly, due to theresonator structure and the color filter layer 76 described above, thethree types of the first sub pixels 33 (r, g, b) which the first pixels31 are configured from can irradiate any one of three primary colors oflight as first display light 5 from the first surface 3. Accordingly,the organic EL device 92 can form a color image on the first surface 3.

As described above, the organic EL device 92 can form a color image onboth surfaces, that is, both surfaces of the first surface 3 and thesecond surface 4. Also, a portion of external light 7 can pass throughthe transmissive region 43, in a similar manner to the region in theorganic EL device 91 relating to the first embodiment. Accordingly, whenthe organic EL device 92 relating to the embodiment is used in a meetingor the like, two people facing each other can look at color images,which are necessary for each of them, while visually recognizing eachother through the organic EL device.

Here, the ratio of light pass through the semi-transmissive layerdescribed above is not limited to approximately 50%. The transmissivityof the semi-transmissive layer may be increased by improvement in thecolor purity further depending on the color filters 75 (r, g, b).

Also in regard to the organic EL device 92 relating to the embodiment,the necessity to suppress the irradiation of display light (5, 6) to theopposite side, that is, irradiation of light to the lower surface 4 sidein the first pixel region 41 and irradiation of light to the uppersurface 3 side in the second pixel region 42, is the same as for theorganic EL device 91 relating to the first embodiment described above.Also, the necessity to suppress the reflecting of external light 7 isalso the same. These phenomena can be suppressed in the first pixelregion 41 as the organic EL device 92 is provided with the black matrix75 k in the color filter layer 76, but may cause problems in the secondpixel region 42.

In order to suppress these phenomena, it is preferable that the pixelelectrodes (35, 36) are formed to be included inside of the reflectinglayers (13, 14) in a plan view in the same manner as the organic ELdevice 91. Also, the effectiveness of also forming a partition in orderto suppress the phenomena described above is the same. By forming thepartition, which is formed of an insulating material with light blockingproperties so as to surround the pixel electrodes (35, 36) in a planview, between the pixel electrodes (35, 36) and the light emittingfunctional layer 15, both the irradiating of emitted light from thelight emitting functional layer 15 toward a nonpreferred side and thereflecting of external light 7 can be suppressed. Also, a light blockinglayer may be formed on a specific region of both rear surfaces of thesubstrates (10, 11), that is, the surface on the opposite side to thesealing layer 79 side. If the light blocking layer is formed on the rearsurface of the element substrate 10 in regard to the first pixel region41 and if the light blocking layer is formed on the rear surface of theopposing substrate 11 in regard to the second pixel region 42,reflecting of external light 7 is suppressed and display quality can beimproved.

Effects of the Embodiment

The organic EL device 92 relating to the embodiment is provided with thefirst pixels 31 which irradiate emitted light (display light) to thefirst surface 3 side and the second pixels 32 which irradiate emittedlight (display light) to the second surface 4 side. By forming the twotypes of pixels in the display region 100, images which are eachdifferent can be formed on both surfaces. Both types of pixels describedabove have common configuration components such as the pixel electrodes(35, 36), driving elements including the TFT 112, the light emittingfunctional layer 15, and the like. Accordingly, the organic EL device 92relating to the embodiment is configured by newly adding thesemi-transmissive reflecting layer (either 12 or 19), the color filters75 (r, g, b), the reflecting layers (13, 14) to an existing (typical)organic EL device which can display color. That is, by the addition ofthe configuration components, forming of images which are each differentis possible by irradiating display light from both surfaces of the firstsurface 3 and the second surface 4. Also, as the organic EL device 92relating to the embodiment has the transmissive region 43, it ispossible for another person to be visually recognized through theorganic EL device 92. Accordingly, when the organic EL device 92 is usedin a meeting or the like, a plurality of people can carry out aconversation while visually recognizing both each other and shared colorimages.

Here, the effects described above also can be obtained by combining twoof the organic EL devices (including transmissive regions 43). However,for a device with this configuration, it is necessary to form two unitsof all of the components of the light emitting functional layer 15 andthe like, so that there is a problem with cost. The organic EL device 92of the embodiment has the characteristics that the effects describedabove can be obtained by a slight addition of manufacturing processes.Here, the area ratio of the three types of the regions (41, 42, 43)formed in the display region 100 is not limited to 1:1:1 but can bearbitrarily set. This is the same as for the organic EL device 91relating to the first embodiment. However, there are limitations on theratio of the sub pixel regions in regard to the first pixel region 41and the second pixel region 42. The configuration where the transmissiveregion 43 may not be provided is also the same as for the organic ELdevice 91 relating to the first embodiment.

Third Embodiment

Next, the third embodiment of this invention is described. An organic ELdevice 93 of the third embodiment is a double-sided display organic ELdevice in the same manner as the organic EL device in the embodimentsdescribed above. The provision of the transmissive region 43 is also thesame. The difference is that color images are displayed on one surface(one side) and black and white images are display on the other surface(other side). Accordingly, the purpose of use and configuration are thesame as both the organic EL device 91 and the organic EL device 92, andthe components are also similar. Therefore, in the description below,configuration components which, are common with configuration componentsof the organic EL devices (91, 92) described above are given the samesymbols and a part of the description is not repeated.

FIG. 3C is a diagram illustrating an arrangement configuration of pixelregions in the display region 100 of the organic EL device 93. As shownin the diagram, the first pixel region 41, which irradiates displaylight to the first surface 3 side (refer to FIG. 9 described later), isconfigured by three types of the first sub pixel regions 51 (r, g, b).On the other hand, the second pixel region 42, which irradiates displaylight to the second surface 4 side (refer to FIG. 9 described later),does not have sub pixel regions, and each of the regions correspondingto the three types of the first sub pixel regions 51 are the secondpixel regions 42. In addition, in between the first pixel region 41 andthe second pixel region 42, the transmissive region 43 is formed whichallows at least a portion of external light to pass through. In the samemanner as the organic EL devices (91, 92) of the embodiments describedabove, external light 7 (refer to FIG. 9 and the like) can pass betweenthe adjacent sub pixel regions (r, g, b) and between the regions (41,42, 43).

FIG. 8 is a circuit configuration diagram of the organic EL device 93relating to the third embodiment. The diagram is equivalent to FIG. 4 ofthe first embodiment described above, and the transmissive region 43(refer to FIGS. 2A and 2B) is not shown in the diagram in the samemanner as FIG. 4. As shown in the diagram, the first pixels 31 areconfigured by three types of sub pixels, the first red sub pixels 33 r,the first green sub pixels 33 g, and the first blue sub pixels 33 b.When corresponding to FIG. 3C, the first red sub pixel region 51 rcorresponds to the first red sub pixel 33 r, the first green sub pixelregion 51 g corresponds to the first green sub pixel 33 g, and the firstblue sub pixel region 51 b corresponds to the first blue sub pixel 33 b.In addition, three of the second pixel regions 42 which are disposed ina line in a row direction each correspond to the second pixels 32.

Both the first sub pixels 33 (r, g, b) and the second pixels 32described above have the organic EL element 29, the TFT 112, the holdingcapacitor 110, and the switching TFT 108. Accordingly, the first subpixels 33 (r, g, b) and the second pixels 32 have substantially the sameconfiguration. Each of the pixels (31, 32) described above and each ofthe first sub pixels 33 (r, g, b) described above are disposed incolumns in the same manner as the organic EL device 91 and the organicEL device 92 described above. That is, identical pixels (31, 32) andidentical first sub pixels 33 (r, g, b) are disposed in the Y direction.

FIG. 9 is a schematic cross-sectional diagram of the display region 100of the organic EL device 93 relating to the third embodiment. As shownin the diagram, the cross-sectional configuration, that is, theconfiguration in the vertical direction of the substrate surface, issimilar to the configuration of the organic EL device 91 shown in FIG. 5and the organic EL device 92 shown in FIG. 7. That is, the color filterlayer 76 is formed in the first pixel region 41 where the first subpixels 33 (r, g, b) are formed. In addition, the second reflecting layer14 is formed on the upper layer of the cathode 19 in the second pixelregion 42 where the second pixels 32 are formed. Between the first pixelregion 41 and the second pixel region 42 is the transmissive region 43which allows external light 7 to pass through the element substrate 10and the opposing substrate 11.

The thickness of the pixel electrodes of the first sub pixels 33 (r, g,b), that is, the first sub pixel electrodes 37 (r, g, b), are eachdifferent, and the resonator structure is formed between the firstreflecting layer 13 and the cathode 19 having semi-transmissivity. Here,in the same manner as the organic EL device 92 described above, thefirst pixel electrode 35 is matched with the first sub pixel electrodes37 (r, g, b). As the sub pixels are individually controlled, light,which has been mixed in an arbitrary ratio, is irradiated from each ofthe first pixel regions 41. Accordingly, color images are formed on thefirst surface 3 side.

In the same manner as the second pixels of the organic EL device 91, thesecond pixels 32 are not provided with the color filter layer 76 nor theresonator structure. Accordingly, there is no function for emphasizinglight with a specific wavelength range, and the emitted light of thelight emitting functional layer 15 is irradiated as second display light6 from the second surface 4 side with hardly any change to thewavelength distribution.

Both the first pixel electrode 35 and the second pixel electrode 36 areformed of ITO. In addition, the first blue sub pixel electrode 37 b andthe second pixel electrode 36 are formed by patterning the same ITOlayer. Accordingly, the layer thickness is substantially the same.However, as the second pixels 32 have no semi-transmissive layer betweenthe light emitting functional layer 15 and the element substrate 10,there is no resonator structure formed between the second reflectinglayer 14 and the element substrate 10. Accordingly, in regard to thesecond pixels 32, there is no emphasizing of light with a wavelengthrange equivalent to blue light. Accordingly, black and white images areformed in the second surface 4 side.

Also in regard to the organic EL device 93 relating to the embodiment,it is preferable to suppress the irradiating of display light (5, 6) tothe opposite side and the reflecting of external light 7 in the samemanner as the organic EL devices (91, 92) of the embodiments describedabove. To that end, in the same manner as the organic EL devices (91,92) of the embodiments described above, it is also preferable that thepixel electrodes (35, 36) are formed to be included inside of thereflecting layers (13, 14) in a plan view, that the partition, which isformed of an insulating material with light blocking properties so as tosurround the pixel electrodes (35, 36) in a plan view, is formed betweenthe pixel electrodes (35, 36) and the light emitting functional layer15, and further that the light blocking layer is formed on a specificregion of both rear surfaces of the substrates (10, 11), that is, thesurfaces on the opposite side to the sealing layer 79 side.

Effects of the Embodiment

As described above, the organic EL device 93 of the embodiment formscolor images on one surface (the first surface 3) thereof, and on theother surface (the second surface 4), forms black and white images ofcontents which are different from the color images described above. Inaddition, due to the transmissive region 43, the opposite side can bevisually recognized through the organic EL device. Accordingly, in thesame manner as the organic EL devices (91, 92) of the embodimentsdescribed above, when the organic EL device 93 is used in a meeting orthe like, a plurality of people can carry out a conversation whilevisually recognizing each other and shared images.

Here, the cross-sectional configuration in regard to the first pixelregion 41 is substantially the same as an organic EL device whichperforms displaying of color images on only one surface using a typicalorganic EL layer (that is, the light emitting functional layer providedwith an organic EL layer) which emits white light. By only newly formingthe second reflecting layer 14 on the other region of the organic ELdevice, that is, the second pixel region 42, black and white images canbe displayed (formed) on the other surface.

In regard to the double-sided display organic EL device, there may becases where it is sufficient if color images are displayed on only onesurface. For example, in the case where it is used in a meeting or thelike, there is a case where color images are displayed only to the sideof visiting clients. The organic EL device 93 of the embodiment canrealize a double-sided display organic EL device which displays colorimages on only one side by a minimum increase in the number ofmanufacturing processes, that is, a minimum increase in manufacturingcosts.

Fourth Embodiment

Next, the fourth embodiment of this invention is described. An organicEL device 94 of the fourth embodiment is a double-sided display organicEL device which displays (forms) color images on one surface anddisplays black and white images on the other surface in the same manneras the organic EL device 93 in the third embodiment described above. Theprovision of the transmissive region 43 is also the same as the organicEL device 93, and components are also similar.

Therefore, in the description below, configuration components which arecommon with configuration components of the organic EL device 93 aregiven the same symbols and a part of the description is not repeated.

FIG. 3D is a diagram illustrating an arrangement configuration of thepixel regions in the display region 100 of the organic EL device 94. Asshown in the diagram, the first pixel region 41, which is a region whichirradiates display light to the first surface 3 side (refer to FIG. 11described later), is configured by three types of the first sub pixelregions 51 (r, g, b) in the same manner as the corresponding region ofthe organic EL device 93. In addition, in a position (region) opposingthe first pixel region 41 via the transmissive region 43, one secondpixel region 42, which is a region which irradiates display light to thesecond surface 4 side (refer to FIG. 11 described later), is formed.

FIG. 10 is a circuit configuration diagram of the organic EL device 94relating to the fourth embodiment. FIG. 10 is a diagram equivalent toFIG. 4 of the first embodiment described above. In the same manner asFIG. 4, as FIG. 10 is a circuit diagram, the transmissive region 43described above is not shown. As shown in the diagram, the configurationof the first pixels 31 is the same as the configuration of the pixelsfor the organic EL device 92 and the organic EL device 93, and is formedof three sub pixels. The configuration of the second pixels 32 is thesame as the configuration of the pixels for the organic EL device 93,and does not have sub pixels. In the case that it is assumed that eachof the first sub pixels 33 (r, g, b) which configure the first pixels 31is one pixel, the ratio of the number of pixels for displaying an imagein the first surface 3 to the number of pixels for displaying an imagein the second surface 4 is 3-to-1 and not 1-to-1. The arrangement of thepixels (31, 32) and the like in the display region 100 and theconfiguration of the second pixels 32 are also similar to thearrangement in the organic EL device 93. That is, the first pixels 31,the second pixels 32 and each of the first sub pixels 33 (r, g, b) whichconfigure the first pixels 31 are formed in columns shown in FIG. 2Adescribed above.

FIG. 11 is a schematic cross-sectional diagram of the display region 100of the organic EL device 94 relating to the fourth embodiment. As shownin the diagram, the cross-sectional configuration of the first pixelregion 41 and the cross-sectional configuration of the transmissiveregion 43 are the same as the cross-sectional configurations of theorganic EL device 93 shown in FIG. 9. The second pixels 32 formed in thesecond pixel region 42 are also a combination of the organic EL element29, the TFT 112, the holding capacitor which is not shown, and the like.This is the same as the second pixels 32 of the organic EL device 93.However, compared to the second pixel 32 of the other embodiments, thesecond pixel electrode 36 is formed slightly larger. As a result, theratio of the first pixel region 41 to the second pixel region 42 issecured as approximately 3-to-2 and not 3-to-1 which is the ratio of thenumber of pixels described above. Due to this configuration, the organicEL device 94 of the embodiment displays color images in the firstsurface 3 and displays black and white images, which have low pixeldensity compared to the color images described above, in the secondsurface 4.

Also in regard to the organic EL device 94 relating to the embodiment,it is preferable to suppress the irradiating of display light (5, 6) tothe opposite side and the reflecting of external light 7 in the samemanner as the organic EL devices (91, 92, 93) of the embodimentsdescribed above. To that end, in the same manner as the organic ELdevices (91, 92, 93) of the embodiments described above, it is alsopreferable that the pixel electrodes (35, 36) are formed to be includedinside of the reflecting layers (13, 14) in a plan view, that thepartition, which is formed of an insulating material with light blockingproperties so as to surround the pixel electrodes (35, 36) in a planview, is formed between the pixel electrodes (35, 36) and the lightemitting functional layer 15, and further that the light blocking layeris formed on a specific region of both rear surfaces of the substrates(10, 11), that is, the surfaces on the opposite side to the sealinglayer 79 side.

Effects of the Embodiment

As described above, the organic EL device 94 of the embodiment realizesa double-sided display organic EL device which displays color images ononly one surface, and displays black and white images on the othersurface in the same manner as the organic EL device 93 of the thirdembodiment. As described above, the organic EL device with thisconfiguration can be realized by addition of a slight cost to a typicalorganic EL device which displays color images on only one surface. Inaddition, the organic EL device 94 of the embodiment can realize displayof black and white images at a lower cost in exchange for a slightreduction in image quality. Accordingly, while increases inmanufacturing costs are further suppressed, a double-sided displayorganic EL device can be realized which is appropriate in cases where itis permissible that there is a further difference in image qualitybetween images displayed on one surface (the first surface 3) and imagesdisplayed on another surface (the second surface 4).

The configurations of the embodiments of the invention are not limitedto the embodiments described above, and various modifications andalternations can be made. Modified examples are described below.

Modified Example 1

In regard to the embodiments described above, the organic EL layerincluded in the light emitting functional layer is an organic EL layerthat irradiates white light. The display of color images is performed ineach sub pixel by emphasizing light with a specific wavelength range inlight included in the white light. However, as an embodiment of theinvention, a configuration is also possible where organic EL layers areindividually formed to match the color of the display light irradiatedby each of the sub pixels. According to this configuration, the colorfilter or the resonator structure can be omitted. Here, the individualorganic EL layers can be formed by an ink injection method or a maskfilm formation method.

Modified Example 2

The organic EL devices of the embodiments described above (except forthe first embodiment) combines use of the color filter and the resonatorstructure in order to emphasize light with a specific wavelength range.However, the emphasizing described above is possible with only either ofthe color filter or the resonator structure. In addition, theconfiguration may be changed by the first pixels 31 and the secondpixels 32. In particular, as forming the color filter on the elementsubstrate 10 side increases the cost, manufacturing costs can besuppressed in exchange for a slight reduction in image quality if thereis a configuration where the second pixels 32 which irradiate light tothe second surface 4 output colored light by using only the resonatorstructure.

Modified Example 3

In the embodiments described above, the organic EL devices 91 to 94 aredescribed as an active matrix type, but may be a passive (simple) matrixtype where the light emitting functional layer is interposed between thescanning electrode and the data electrode. Even in this configuration,by forming reflecting layers (13, 14) on both sides of the lightemitting functional layer 15, double-sided display is possible using asingle light emitting functional layer.

The entire disclosure of Japanese Patent Application No. 2009-287303,filed Dec. 18, 2009 is expressly incorporated by reference herein.

What is claimed is:
 1. A light-emitting device comprising: a pluralityof the light emitting elements that is disposed between a firstsubstrate and a second substrate, the light emitting elements having afirst light emitting element emitting a light through the firstsubstrate and a second light emitting element emitting a light throughthe second substrate; a transmissive region that is disposed between thefirst light emitting element and the second light emitting element inplan view, the transmissive region transmitting a light through thefirst substrate and the second substrate.
 2. A light-emitting devicecomprising: a plurality of the light emitting elements that is disposedbetween a first substrate and a second substrate, the light emittingelements having a first light emitting element emitting a light throughthe first substrate and a second light emitting element emitting (FIG.5; 41) a light through the first substrate; a transmissive region thatis disposed between the first light emitting element and the secondlight emitting element in plan view, the transmissive regiontransmitting a light through the first substrate and the secondsubstrate.
 3. The display device according to claim 1, the first lightemitting element having a first pixel electrode, a second electrode. anda light emitting layer disposed between the first pixel electrode andthe second electrode, the second light emitting element having a secondpixel electrode, the second electrode, and the light emitting layerdisposed between the second pixel electrode and the second electrode. 4.The display device according to claim 3, the first light emittingelement having a first reflecting layer disposed between the first pixelelectrode and the first substrate, the second light emitting elementhaving a second reflecting layer disposed between the second pixelelectrode and the first substrate.